The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In general, a vehicle is equipped with many electric motors, which generate torque necessary for operating devices by receiving power from a battery and supply the torque to the devices.
In order to control a motor, which is a rotary device, it is necessary to precisely and rapidly detect information about rotation of the motor. In particular, movement or a position of a rotary shaft must be measured accurately through detection of an angle of a rotor.
One of essential devices of a vehicle, which use a motor, is a motor-driven power steering (MDPS) system, which supplements the steering force applied by a driver using the power of the motor.
In the motor-driven power steering system, it is necessary to control a motor precisely. Therefore, the motor-driven power steering system requires a device capable of precisely detecting the angle of a rotor of a motor.
In addition, in eco-friendly vehicles, such as pure electric vehicles, hybrid electric vehicles and fuel cell electric vehicles, a motor is used as a drive source for driving the vehicle.
These eco-friendly vehicles are equipped with an inverter system for driving and controlling the motor, and a resolver is used as a position sensor for detecting the absolute angular position (θ) of a rotor of the motor, which is used to control the motor.
In order to perform vector control of a motor, a coordinate system needs to be set in synchronization with the magnetic flux position of the motor. To this end, it is necessary to read the absolute angular position of a rotor of the motor.
Accordingly, a resolver is used to detect the absolute angular position of the rotor of the motor. Each phase of the rotor of the motor is accurately sensed using the resolver, with the result that it is possible to perform motor speed control and torque control.
In general, the resolver includes a rotor, which a rotary shaft of a motor penetrates, and a ring-shaped stator, which faces the rotor while being spaced a predetermined gap apart from the rotor. Coils of the rotor and the stator are wound so that their magnetic flux distributions become sine waves corresponding to particular angles.
If excitation signals (M_REZ+ and M_REZ−) are applied to a primary-side coil (an input terminal), which is wound around a rotor of a resolver, and the rotor of the resolver is rotated by a rotary shaft of a motor (a rotor of a motor), the magnetic coupling coefficient is changed, and accordingly signals each having a carrier, the amplitude of which is changed, are generated in a secondary-side coil (an output terminal), which is wound around a stator of the resolver. In this case, the coils are wound so that the signals have cosine (cos) and sine (sin) forms depending on rotation angles (θ) of the rotor of the motor and the rotor of the resolver.
In the resolver, the rotor includes a plurality of salient poles, which are formed along the outer circumference thereof, and the ring-shaped stator includes a plurality of teeth and a plurality of slots, which are alternately formed along the inner circumference thereof. Coils of the stator are received in the slots while being wound around the teeth.
However, a conventional resolver has no special structure designed to protect coils, and thus the coils may be easily damaged by external physical impacts or force. Moreover, the bonding force or coupling force between components of the resolver is low.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.